I don't know how you converted density to mols/cc and 55.85/0.141 is not 7.10 BUT 55.85/7.871 = 7.095 g/cc which rounds to 7.10 g/cc and that is the correct answer.
As for the volume, after reading some of your earlier posts, especially the one about the crystal structure of iron, I wonder if the problem intended for you to go through the unit cell business.

By the way, if you are the same John that posted earlier about the boiling point of 2-propanol, I have posted a response to that at the original post. There are two or three things wrong with the way you did it although the Clausius-Clapeyron equation is the correct way to go.